Crank shaft



Aug, ma wma www-@ R. HlLDEFAND CRANK SHAFT Filed DeC. 50,. 1920 WIUvESSES: ENVEMTQR:

Patented Aug, l2, i924.

REINHARD HILID'EBRAND, OF WEBSTER GROVES, MISSOURI,\ASSIGNOR TO FULTON IRON WOR-KS COMPANY, OF ST. LOUIS, MISSOURI, A CORPORATION OF DELAW'ARE.

o CRANE SHAFT.

Application filed December 30, 1920.

To all 'whom t may concern:

Be it known that I, REINHARD HILDn- BRAND, a citizen of Germany, and a resident ofi Webster Groves, in the county of St. Louis and State of Missouri, have invented a new and useful Crank Shaft, of which the following is a specification.

My invention relates to built up crank shafts and its object is to obtain a better and stronger shaft than used heretoforel The drawing shows my invention, embodied in a crank shaft. The shaft proper is designated by the letters A and B, the crank arms are marked C and D and the crank pin is indicated by the letter E The shaft A and B and the pin E are pressecll) or shrunk into `the crank arms 4CH C 77.

It will be noticed that the ends of the shafts and the ends of the pin are stepped down to a smaller diameter. These reduced shaft ends and pin ends are designated by the letters a and Z9 and by e and el, respectively. The object of stepping down the shaft ends and pin ends is to reduce the corresponding apertures in the crank arms C and D, thus obtaining a greater amount of material at the places C1, C2, C., and C4b in the crank arms, compared with the design heretofore used which does not have reduced shaft and pin ends.

This increase of material in the crank arms at the `places C1, C2, C3, and CL, is of great importance which will be understood if the manner of assembling a built up crank shaft is considered. For this reason the method of assembling a built up crank shaft shall be explained:

First, the pin E is pressed or shrunk into the crank arms C and D. The holes for the shaft A and B which were previously rough bored into the crank arms C and D are now finished and the shaft ai andA B pressed or shrunk into the arms. This pressing or shrinking the shaft A and B into the crank arms C and D tends to stretch the' material of the crank arms at the places C1, C12, C3, and C4, disturbing the press or shrink fit of the pin E, causing the pin to become loose in the crank arms. Quite a number of failures of built up crank shafts are caused by insufficient crank arm material at the places C1, C2, C3 and C4. Now it will be fully un- 'y derstood that the strength of my built up Serial No. 434,175.

crank shaft is increased by decreasing the diameters of the shaft ends and pin ends, thus, decreasing their corresponding apertures in the crank arms.

Each shaft member A and B is provided with a tapering shoulder and a reduced end portion extending therefrom, and the crank pin E is likewise provided with tapering shoulders and reduced end portions extending therefrom. Each crank arm is closely fitted to a shaft member and crank pin at points on opposite sides of the tapering shoulders, and these shoulders are surrounded by correspondingly tapered shoulders in the crank arm.

Referring again to the drawing, F rep resents oil slings which throw off the oil coming from the shaft bearings. The circular groove Gr the drilling IL-I and I are provided to furnish oil to the crank pin, the oil being introduced into the groove G Numerous changes could be made which would fall in the scope of my invention. In particular, I do not confine myself to built up center crank shafts, as end crank shafts can be made in a similar manner.

hat I claim as new is :w-

1. A crank arm provided with a stepped off aperture and a circular concentric oil groove around said aperture, and a passage from said oil groove leading to the bearing surface of the crank pin.

l2. The combination of a shaft having a tapering shoulder, a relatively large straight portion at one side of said taper ing shoulder and a reduced straight end portion extending from the other side of said tapering shoulder, a crank pin having a tapering shoulder, a relatively large straight portion at o-ne side thereof and a reduced straight end portion extending from the other side, and a crank arm having apertures, each of which comprises a tapering wall portion, a relatively large straight wall portion at one side of said tapering wall portion, and a reduced straight wall portion extending fromf'the other side of said tapering wall portion, the walls of said apertures being in contact with and closely tted to the respective straight portiers of the shaft and crank pin.

REINHARD HILDEBRAND, i/Vitnesses:

CHAs. P. GLAnsn, Jr., WALTER A, GANTNER, 

